Tropical Storm Andrea moved briskly along the South Carolina coast on Friday, bringing drenching rains and threatening to spawn tornadoes as it churns up the Eastern Seaboard, U.S. forecasters said.
Andrea, the first named storm of the Atlantic hurricane season, weakened slightly a day after lashing parts of Florida and southern Georgia with driving rains and high winds.
On Friday, Andrea carried top sustained winds of 45 miles (72 km) per hour and was centered 35 miles (60 km) north-northeast of Charleston, South Carolina, the National Hurricane Center said.
The storm gained speed overnight and was expected to move quickly up the East Coast, said Jack Beven, a hurricane specialist at the Miami-based center.
"It's likely to continue a fast motion towards the Northeast during the next day or so," he said.
In South Carolina, authorities said there were no immediate reports of injuries or damage. Scattered power outages were reported in the state, with 2,500 customers losing service.
Tropical storm warnings were in effect for the U.S. Atlantic Coast from South Carolina to Virginia, including the lower Chesapeake Bay, and forecasters warned tropical storm conditions will continue to spread northward in the area.
Andrea could cause tornadoes in coastal areas from North Carolina through Virginia, the hurricane center said.
The storm buffeted Florida's western coast on Thursday, fueling several tornadoes, including one that ripped a roof off a restaurant in the city of Gulfport. After swirling over the Gulf of Mexico, the storm made landfall over the Big Bend area, where the Florida peninsula joins the mainland.
The Atlantic hurricane season runs from June 1 to Nov. 30.
The U.S. government's top climate agency warned in an annual forecast last month that this year's season could be "extremely active" with 13 to 20 tropical storms, seven of 11 of which are expected to become hurricanes.
Three to six hurricanes could become major at Category 3 or above, with winds of more than 110 mph (177 kph), the National Oceanic and Atmospheric Administration said.